RICHMOND — Virginia Gov. Ralph Northam (D) faced the national uproar over a racist photo from his 1984 medical school yearbook on Saturday and refused to resign, defying nearly the entire Democratic establishment and insisting that it was not his picture.

“I am not the person in that photo that caused this stir,” Northam told media packed into the Executive Mansion, referring to the image of a person dressed in blackface and another in a Ku Klux Klan robe on his yearbook page.

“Last night I finally had a chance to sit down and look at the photo in detail,” said Northam, adding that he does not own the yearbook and that it was the first time he had ever seen the photo. “It is not me.”

It was a complete and puzzling turnaround from the day before, when Northam apologized for appearing in a “clearly racist” photo in the yearbook. But even as he denied being in the photo, he acknowledged he once applied black shoe polish to his face to appear as Michael Jackson in a dance competition.

Northam’s comments seemed to have the opposite effect than intended. Calls for his resignation intensified from leaders across the country. The loudest came from state and national Democrats, with some even wondering about impeachment.

“We amplify our call for the Governor to resign,” the Virginia Legislative Black Caucus, a key Democratic constituency and onetime ally of Northam’s, said in a statement. “Our confidence in his ability to govern for the over 8 million Virginians has been eviscerated.”

After the news conference, the state’s two Democratic senators, Mark R. Warner and Tim Kaine, and Rep. Robert C. “Bobby” Scott (D), the dean of the Virginia congressional delegation, called Northam and told him he needed to step down.

L. Douglas Wilder, the former Virginia governor and first African American to lead a state since Reconstruction, said, “It is difficult for anyone who watched the press conference today to conclude that (Northam) has any other choice . . . but to resign.”

The governor, 59, struggled to explain himself at his news conference, saying that when the image first became public Friday afternoon, the public reaction was so swift and intense, he felt compelled to apologize.

But he said he now believes there was a mix-up at publication that allowed someone else’s photo to get printed on his yearbook page. He said his staffers were investigating and they might use facial-recognition software to confirm his suspicions.

Two classmates of Northam’s at Eastern Virginia Medical School said Saturday that they had never seen him in costumes like those that appear in the photo on his yearbook page. However, they were at a loss to explain how a mix-up might have occurred that would result in the racist image being placed on his page in error, because students were responsible for submitting their own photos.

The vast majority of the pages in the medical school yearbook contained standard photos of graduates in business clothes and family snapshots. Northam’s page stood out, along with one other on a nearby page.

Throughout the news conference, carried live on national television, Northam repeatedly spoke about his honor. Above all else, the governor sees himself as a man of integrity, and he was painfully aware that most of his listeners thought he was lying, so he worked hard to convince them he was telling the truth.

The governor’s wife, Pam Northam, stood to the right of her husband, looking grim, as he fielded questions and tried, again and again, to explain himself.

The son of a circuit court judge, Northam served as president of the Honor Court his senior year at Virginia Military Institute. Known among students as “the pope,” the position is considered the most prestigious at the university, one that sits in judgment of any student accused of lying or violating the honor code. Northam recited the code during his news conference: “A cadet will not lie, cheat, steal, nor tolerate those who do.”

“I tell the truth,” he said. “I’m telling the truth today.”

Whether they believed him or not, most Virginia leaders said the damage was beyond mending in a state that is marking the 400th anniversary of the arrival of the first Africans in America, brought on slave ships.

If Northam were to leave office, he would be succeeded by Lt. Gov. Justin Fairfax (D), who would become just the fourth African American governor in modern U.S. history.

Virginia Attorney General Mark R. Herring (D) called on Northam to resign.

“It is no longer possible for Governor Northam to lead our Commonwealth and it is time for him to step down,” Herring said. “I have spoken with Lieutenant Governor Fairfax and assured him that, should he ascend to the governorship, he will have my complete support and commitment to ensuring his success and the success of our Commonwealth.”

Herring had announced his intention to run for governor in 2021 in what was expected to be a primary fight between Herring and Fairfax.

If Fairfax becomes governor, he would serve the three remaining years of Northam’s term and be in a strong position to run for a full four-year term.

Northam met with Fairfax early Friday evening and apologized for the photo, telling him at the time that he had no memory of it but that he took responsibility because it was on his page, Fairfax told reporters Saturday.

“He said at the time, ‘I don’t recall the party or taking that particular photo, but it’s on my page and I’m sorry,’ ” Fairfax said.

National Democrats, concerned that Northam will become a liability for 2020 Democratic hopefuls and threaten Democratic control of an important swing state, were unrelenting in their demands that he step aside. After speaking with Northam, Tom Perez, chairman of the Democratic National Committee, released a statement that said Northam had lost his ability to govern.

Derrick Johnson, president of the NAACP, was even more strident.

“We are deeply disappointed in Gov. Ralph Northam’s decision to not resign today,” he said. “His failure to take accountability for his actions is sickening.”

The head of the state Republican Party immediately called for Northam’s resignation on Friday, and House Speaker Kirk Cox (R-Colonial Heights) and Senate Majority Leader Thomas K. Norment Jr. (R-James City) followed suit on Saturday.

Cable television devoted hours to the controversy, and social media lit up with #ResignRalph hashtags. Calls to resign also came from former vice president Joe Biden — who had campaigned for Northam — and House Speaker Nancy Pelosi (D-Calif.), as well as Democratic presidential hopefuls Sen. Elizabeth Warren (Mass.), Sen. Kamala D. Harris (Calif.), Sen. Kirsten Gillibrand (N.Y.), Sen. Cory Booker (N.J.) and Julián Castro, a former mayor of San Antonio.

If Northam resigns, he would be the first Virginia governor to step down while in office since the Civil War.

With the Democratic leadership lined up against him, Northam huddled Friday and Saturday with advisers, his pastor and his family, discussing a completely different outcome to the saga: He wanted to soldier on and use the episode to heal the state’s racial divisions.

Still, he alluded to other actions in his past and disclosed that in 1984 he won a dance contest in San Antonio where he wore dark shoe polish on his cheeks as part of a Michael Jackson costume. He seemed ready to demonstrate his moonwalk in response to a reporter’s question, but the teary-eyed first lady dissuaded him.

“I have made mistakes in my past, but I am a person of my word, I have great friends on both sides of the aisle,” Northam said. “I will work hard to maintain their faith in me and my ability to lead, and hopefully together we’ll move forward.”

Northam said if he felt he wasn’t able to function effectively, he would revisit the issue “and make decisions.”

Until this point, Northam had enjoyed strong approval ratings from voters. A December poll from the Wason Center for Public Policy at Christopher Newport University found 59 percent of voters — including 32 percent of Republicans — approved of Northam’s performance as governor.

On Saturday, many of those voters were unsure what to think of their governor.

“I’m really torn and upset,” said Juanita Gartman, 62, a nurse and former union organizer from Nokesville, south of Manassas. “I don’t know what he should do, to be honest.”

She condemned the photo but could not bring herself to call for his resignation.

“It was an incredibly stupid thing for him to do, even in 1983,” she said. “If Northam needs to resign, so does [Supreme Court Justice Brett] Kavanaugh and Trump. People make horrible mistakes, and this is going to hurt him politically if he stays there, because the Republicans smell blood.”

Ivania Castillo, 52, voted for Northam for governor and met him several times. While she loves what he has done in office, she thinks he has to resign.

“He is kind, soft, very close to the Hispanic community,” said Castillo, an immigrant from El Salvador who works for Casa in Action in Prince William County. “For me, I cried when I saw that picture. It’s very racist, and the pain that the African American community feels now is like the pain we feel from Donald Trump and his government.”

The image in the yearbook from Eastern Virginia Medical School was on a page with other photos of Northam and personal information about the future governor. Northam, a pediatric neurologist, graduated from the medical school in Norfolk in 1984 after earning an undergraduate degree from VMI.

The yearbook page is labeled “Ralph Shearer Northam” and has photos of him in a jacket and tie, casual clothes and alongside his restored Corvette.

Another photo shows two people, one in plaid pants, bow tie and blackface and the other in a Klan robe. Both appear to be holding beer cans. The person in blackface is smiling. Beneath the photo, Northam lists his alma mater and his interest in pediatrics and offers a quote: “There are more old drunks than old doctors in this world so I think I’ll have another beer.”

Tobin Naidorf, who also graduated in 1984 and is now a gastroenterologist in Alexandria, said he did not recall the exact procedure for submitting photos to the yearbook staff. However, he said he was the only person who could have submitted the family photos that appeared on his own page.

The yearbook image was first posted Friday by the website Big League Politics, a conservative outlet founded by Patrick Howley, a former writer for the Daily Caller and Breitbart.

The Washington Post independently confirmed the authenticity of the yearbook by viewing it in the medical school library in Norfolk.

The revelation comes after a wild week for Northam, who was accused by Republicans of advocating infanticide after he made comments defending a bill that would have lifted restrictions on late-term abortions. It was more surprising because Northam has billed himself as the political antidote to Donald Trump — an aw-shucks leader with a boring speaking style and a reputation for honesty. He gained the trust of Republicans, who worked with him last year to pass Medicaid expansion in the state after four years of resisting it under the previous governor, Terry McAuliffe (D).

Northam grew up on the Eastern Shore of Virginia in the fishing village of Onancock. His father was a judge and his mother a schoolteacher. Northam and his brother attended a desegregated public high school, where Northam played basketball and baseball.

Northam has built his 12-year political career on a clean-cut image as a soft-spoken doctor and Army veteran who has volunteered at a pediatric hospice.

First elected to the state Senate from Norfolk in 2007, Northam has had a charmed political career. He was courted by Republicans because of his conservative leanings and was identified early by Kaine, who was then governor, as gubernatorial material because of his experience in both health care and the military. Northam served in the Army for eight years after medical school and treated soldiers wounded in the Persian Gulf War.

After serving as McAuliffe’s lieutenant governor, Northam ran for governor in 2017 and easily beat Republican Ed Gillespie, whom he accused of running racist attack ads against him.